Resetting apparatus

ABSTRACT

Apparatus for resetting a stepable roller of a counting mechanism. The resetting apparatus includes a cam surface that faces the axis of rotation of the roller. The cam surface extends away from the axis and preferably terminates adjacent the circumference of the roller. A finger mounted on a resetting lever is adapted to engage the cam surface. Means are also provided for moving the finger from a position adjacent the axis of rotation toward the circumference of the roller so that the cam surface is engaged and the roller is thereby rotated to its starting position.

United States Patent 1111 3,552,644

[72] Inventor Alfred Zielke [56] References Cited Peine, Germany UNITED STATES PATENTS J J- 3 3,053,441 9/1962 Vroom 235 144 3,122,315 2/1964 Krebsdzio.. 235/144 [45] :i g -ggg M h b 3,248,051 4/1966 Kelch 235/144 ss'gnee 8 m H 3,368,750 2/1968 Bottling 235/144 Pelne, Germany [32] Priority Mayll,l968 Primary Examiner-Richard B. Wilkinson [33] Germany Assistant Examiner-Stanley A. Wal

[31] N0, P1,774,253 Atlorney-Bair, Freeman & Molinare ABSTRACT: Apparatus for resetting a stepable roller of a counting mechanism. The resetting apparatus includes a cam [54] RESETTING F Q surface that faces the axis of rotation of the roller. The cam 6 Clams 3 Drawmg surface extends away from the axis and preferably terminates [52] U.S. Cl 235/144, adjacent the circumference of the roller. A finger mounted on 235/1 a resetting lever is adapted to engage the cam surface. Means [51] lnt.Cl G07g 1/00, are also provided for moving the finger from a position ad- G06c 15/42 jacent the axis of rotation toward the circumference of the [50] Field of Search ..235/144HC, roller so that the cam surface is engaged and the roller is 1.2, 144 Misc, 144 Rakg thereby rotated to its starting position.

PATENTEB JAN 51971 3,552,644

INVENTOR.

AT TORNEYS RESE'ITING APPARATUS BACKGROUND OF THE INVENTION This invention relates to resetting apparatus for rollers, and is more specifically directed to resetting apparatus adapted for use in connection with the digit rollers of a counting mechanism.

Resetting apparatus is required in a variety of mechanisms. For example, such apparatus is generally employed in counting mechanisms which use electrical pulses or mechanical signals for the advancement of digit rollers. Such a mechanism must be periodically returned to its starting position in order to begin a new counting sequence. Similar resetting apparatus is generally employed in stopwatch fabrication.

All known resetting devices used in connection with a digit roller consists of a laterally protruding, heart-shaped cam that is attached to the side of the digit roller. Each cam is acted on by a resetting finger that is adapted to move from the circumference of the roller toward the rollers axis of rotation. When the resetting finger is moved in the manner described, the roller is turned until the resetting finger reaches a predetermined position on the cam. The resetting finger then snaps into a trap that is provided in the surface ofthe cam. In theory, when the resetting finger is engaged in the trap, the roller is reset in its starting position,

' Resetting devices of the foregoing type have a number of disadvantages. One great disadvantage is that the cam trap is located adjacent the rollers axis of rotation. Accordingly, positioning errors occurring at the cam trap occur adjacent the axis. Of course, these positioning errors result in substantially larger errors at the circumference of the roller. For ex ample, if the cam trap is imperfectly positioned by a fraction of a millimeter, the inaccurate setting at the circumference of the roller is on the order of millimeter magnitudes. Positioning errors of a few fractions of a millimeter are almost impossible to avoid at the axis of rotation due to bearing play in the roller and in the lever used to mount the resetting finger.

Positioning errors are particularly undesirable in systems that provide a gear connected adjacent the circumference of each roller. Such gears are typically provided in counting mechanisms wherein the individual digit rollers are advanced by transfer pinions. A pinion normally engages the gears of adjacent rollers, thereby advancing oneroller by one digit when the other roller has completed one revolution. In such mechanisms, each transfer pinion is deflected or disengaged from its associated gears during the resetting of the digit rollers. After the resetting operation is completed, the transfer pinions are brought back into engagement with their respective digit roller gears. If the digit rollers are not precisely positioned during the resetting operation, the transfer pinions may not mesh with the gears. For example, the tooth of a transfer pinion may strike the tooth of a gear instead of engaging in a tooth gap thereof. Such a malfunction can result in blockage or other disturbance of the mechanism.

The danger of the above-described malfunction is increased in normal counting mechanisms since the respective distancesfrom the axis of rotation to the cam'trap and to the circumference of the roller have a ratio of about 1:5. As a result, positioning imperfections in the area' of the cam trap are multiplied by five in the area adjacent the circumference of the roller. For example, a tolerance variation of 0.2 mm. adjacent the cam trap yields a positioning inaccuracy of about I mm. at the circumference of the digit roller. Such positioning inaccuracies are extremely difficult to avoid. A 0.2 mm. setting inaccuracy adjacent the cam trap may be present due to a bearing error in the digit roller, manufacturing imperfections of the cam trap, bearing error in the resetting finger or parts as sociated therewith, and differences in the width of the resetting finger and cam trap. The foregoing types of errors must be held to extremely close tolerances in order to avoid errors at the circumference of the-roller that prevent the transfer pinions from properly engaging the gears of the rollers.

SUMMARY OF THE INVENTION In order to overcome the deficiencies of the prior art apparatus, and to achieve the foregoing objects, the present invention, in principal aspect, basically comprises a cam surface that faces the axis of rotation ofa roller included in a counting mechanism. The cam surface is connected to the roller and extends toward the circumference thereof. A finger is provided for engaging the cam surface. Means are also provided for moving the finger from a position adjacent the axis of rotation toward the circumference of the roller. When the finger is moved in the foregoing manner, the cam surface is engaged by the finger, and the roller is rotated about its axis toward a predetermined starting position.

The advantages of the present invention are at once apparent. By providing a cam surface in which the starting position of the roller is determined by a portion ofthe cam surface displaced from the axis of rotation, positioning errors at the circumference of the roller are substantially reduced. If the cam surface is extended substantially to the circumference of the roller, positioning errors are transmitted to the, circumference of the roller in a 1:1 ratio, thereby eliminating the multiplication of positioning errors that is present in prior art devices.

By using the apparatus described herein, the repositioning of rollers is substantially increased in accuracy. As a result.

larger manufacturing tolerances can be used for all critical parts, thereby significantly decreasing the cost of production.

DESCRIPTION OF THE DRAWING These and additional objects, advantages, and features of the present invention will hereinafter appear for purposes of illustration, but not of limitation, in connection with the accompanying drawing in which like numbers refer to like parts throughout, and in which:

FIG. 1 is a side elevational view of a preferred form of resetting apparatus made in accordance with the present invention and shown in connection with an exemplary digit roller;

FIG. 2 is a front elevational view of the apparatus shown in FIG. 1; and

FIG, 3 is a cross-sectional view taken along line III-III in FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to the drawing, an exemplary digit roller 1 has a circumferential surface 8 on which there are arranged digits 4. To one side of the roller is connected a gear 2 having individual teeth 3 pointed radially outward. On the same side of gear 2 there is mounted a generally heart-shaped cam 5 which has the same lateral width as gear 2. The cam has a cam surface Sa that faces the axis of rotation 6a and axial bore 6 of the digit roller. A cam trap 7 is located at the point of the cam farthest removed from axial bore 6. Trap 7 is constructed as a recess between two teeth 3 of gear 2. The side of the digit roller opposite gear 2 is reduced in thickness under its circumferential surface 8 for the reduction of weight. A collar 9 provides a secure bearing surface for the rotation of the digit roller about its axis of rotation.

A resetting finger 10 in the form of a round bolt having a longitudinal axis 10a extending in the direction of axial bore 6 is positioned within cam 5. Finger I0 is mounted on a resetting lever 11 extending perpendicularly -to the finger. During operation of the resetting device} the resetting lever I I is swung laterally toward the circumference of roller I (i.c.,- counterclockwise as viewed in FIG. -I) so that resetting finger 10 engages surface 5a and, in the p roccss, cxerts a torque on digit roller 1. The digit roller is consequently swung on its axis of rotation until the resetting linger 10 has reached the point of surface 5a most remote from axial bore 6. The finger then slips into cam trap 7. The resetting finger has a diameter which corresponds to the width of cam trap 7, so that digit roller 1 is arrested in its starting position by the engagement of the resetting finger in the cam trap. Digit roller 1 is thereby held against additional movement.

By using resetting apparatus of the type described, digit roller 1 is more precisely returned to its starting position than by using known resetting devices. As a result, the manufacturing tolerances of the resetting mechanism can be increased without adversely affecting performance.

Those skilled in the art will appreciate that certain structural and operational features of the apparatus disclosed herein may be altered without departing from the spirit and scope of the invention. For example, the point of cam 5 most remote from the axial bore 6 may terminate in a point rather than a trap of the type described. Furthermore, resetting finger 10 can be differently constructed and can, for example,

roller comprising:

a cam surface that faces said axis and extends toward the circumference of said roller, said cam surface being connected to said roller;

a finger for engaging said cam surface; and

means for moving said finger from a position adjacent said axis toward the circumference of said roller whereby said cam surface is engaged and said roller is rotated about its axis.

2. Apparatus, as claimed in claim 1, wherein said cam surface is substantially heart-shaped.

3. Apparatus, as claimed in claim 1.;wherein said roller is moved by means of a gear attached thereto, and wherein said cam surface extends to a position adjacent the circumference of said gear.

4. Apparatus, as claimed in claim 1, wherein said cam surface is interrupted at the position in which said surface is most remote from said axis for forming a trap having a width corresponding to the width of said finger.

5. Apparatus, as claimed in claim 4, wherein said trap is located adjacent the circumference of said roller.

6. Apparatus, as claimed in claim 1, wherein said finger comprises a round bolt having a longitudinal axis extending parallel to said axis of said roller, and further comprising a resetting lever connected to said finger and arranged perpendicular to said longitudinal axis. 

1. In a counting mechanism having a movable roller that is rotatable around an axis, improved apparatus for resetting the roller comprising: a cam surface that faces said axis and extends toward the circumference of said roller, said cam surface being connected to said roller; a finger for engaging said cam surface; and means for moving said finger from a position adjacent said axis toward the circumference of said roller whereby said cam surface is engaged and said roller is rotated about its axis.
 2. Apparatus, as claimed in claim 1, wherein said cam surface is substantially heart-shaped.
 3. Apparatus, as claimed in claim 1, wherein said roller is moved by means of a gear attached thereto, and wherein said cam surface extends to a position adjacent the circumference of said gear.
 4. Apparatus, as claimed in claim 1, wherein said cam surface is interrupted at the position in which said surface is most remote from said axis for forming a trap having a width corresponding to the width of said finger.
 5. Apparatus, as claimed in claim 4, wherein said trap is located adjacent the circumference of said roller.
 6. Apparatus, as claimed in claim 1, wherein said finGer comprises a round bolt having a longitudinal axis extending parallel to said axis of said roller, and further comprising a resetting lever connected to said finger and arranged perpendicular to said longitudinal axis. 